Quantification of sheath blight pathogen infesting swarna rice cultivar in the alluvial zone of West Bengal, India

Abstract

West Bengal, a coastal lying subdivision of India, is the largest producer of rice in India. Swarna (MTU-7029) is a short duration cultivar and commonly grown under the alluvial zone of West Bengal due to its high production value. Present status of rice sheath blight was studied in the major rice (Swarna cultivar) growing Gangetic alluvial zone of West Bengal, India, during Kharif 2013-2016 through a rice production-oriented survey. Twenty-four rice growing locations were clustered into three groups based on the disease infestation level. Linear Discriminant Analysis was used to discriminate three clusters predicated on their infestation level. Results showed a consequential increase in infestation as well as yield loss during the study period. A maximum relative lesion height was detected during heading to dough stage of the crop. Analysis of the area under disease progress curve (AUDPC) shown an increment from Kharif 2013 (864.03) to Kharif 2016 (1286.69). Epidemiological studies revealed that maximum incidence of sheath blight was favored when the temperature swings between 25.8 °C and 32.1 °C, along with a variation of relative humidity between 83.1% and 98.5% and a rainfall amounting 10.98 mm. The results revealed that monoculture of rice was responsible for increasing the infestation of sheath blight of rice at the alluvial zone of West Bengal.